Evaluation of radio frequency microcoils as nuclear magnetic resonance detectors in low-homogeneity high-field superconducting magnets
Evaluation of radio frequency microcoils as nuclear magnetic resonance detectors in low-homogeneity high-field superconducting magnets
复制标题
DOI：
10.1063/1.1149201
复制
发表时间：
1998-11
影响因子：
1.6
通讯作者：
A. Wright;T. A. Neideen;R. Magin;James A. Norcross
中科院分区：
文献类型：
--
作者：
A. Wright;T. A. Neideen;R. Magin;James A. Norcross
我们在这里描述了评估具有亚毫米尺寸（微线圈）的螺线管射频探针作为极低均匀性（100 ppm/cm）磁场中液体核磁共振（NMR）检测器的性能的实验。性能基于测量的H2O线宽。用蒸馏水填充一系列具有样品体积为8、53和593 nl的螺线管微线圈，并在稳定在5.9 T（1H频率=250 MHz）的垂直孔超导磁体中评价最小可获得的未匀场NMR光谱线宽。最小的微线圈（直径472 μm）给出了525 Hz的最小H2O线宽，比来自标准5.7 mm探针的线宽小25倍。线宽随样品体积的平方根增大而增大。为了比较，还测量了在高均匀性（0.1ppm/cm）NMR磁体中使用相同微线圈的匀场H2O线宽。高均匀性磁体的匀场线宽小两个数量级，并表现出类似的深度。
We describe here experiments evaluating the performance of solenoidal radio frequency probes having submillimeter dimensions (microcoils) as detectors for liquid nuclear magnetic resonance (NMR) in very low-homogeneity (100 ppm/cm) magnetic fields. Performance is based on the measured H2O linewidth. A series of solenoidal microcoils having sample volumes 8, 53, and 593 nl were filled with distilled H2O and evaluated for smallest obtainable unshimmed NMR spectral linewidths in a vertical bore superconducting magnet, stabilized at 5.9 T (1H frequency=250 MHz). The smallest microcoil (472 μm diameter) gave a smallest H2O linewidth of 525 Hz, 25 times smaller than that from a standard 5.7 mm probe. Linewidth increased approximately as the square root of sample volume. For comparison, shimmed H2O linewidths using the same microcoils in a high-homogeneity (0.1 ppm/cm) NMR magnet were also measured. Shimmed linewidths in the high-homogeneity magnet were two orders of magnitude smaller and exhibited a similar dep...